This invention relates to a rotor shaft for helicopters.
Rotor shafts mounted on helicopters at present normally comprise a main vertically disposed rotating shaft which is connected to a drive unit by way of a reduction gear box, and carries a blade support hub at its upper end.
In known rotor shafts, the cyclic pitch and collective pitch variations are transmitted to the blades by an assembly of levers controlled by a "swivel plate" device mounted on the outside of the main shaft and controlled by a plurality of jacks, the exit rods of which extend along the main shaft and parallel to it.
As the entire rotor shaft structure normally extends above the helicopter body, the aforesaid delicate devices for controlling the cyclic pitch and collective pitch of the rotor blades are generally particularly vulnerable in that they are directly exposed to all external agents.